We seem to be getting away from my original question which is, for maximum performance (which is all I am interested in) should I leave the dump valve on? I guess the chatter when I take my foot off the "loud" pedal is the turbo slowing down real quick as there is a pressure build up in the intercooler and cannot pump any more. As I understand it the dump valve releases that built up pressure back in to the turbo on the intake side to spin the turbo up again. This I would see as helping the situation not hindering it. Am I right?